It is known in the art, for example, as disclosed in Japanese Patent Publication No. 2003-65694, that a heat exchanger comprises a core portion having multiple tubes and fins, which are alternately stacked in a vertical direction, a pair of reinforcing elements (side plates) provided at both vertical sides of the core portion, and mounting brackets fixed to the reinforcing elements for mounting the heat exchanger into an engine compartment of a vehicle.
In the above prior art, the mounting bracket has a U-shape in its cross-section and opening to the reinforcing elements. A projection is formed on a flat bottom portion (first wall portion) of the mounting bracket. The mounting bracket has a pair of downwardly bent wall portions (second wall portions) formed with multiple mounting holes. Multiple mounting bolts are inserted through the mounting holes and fixing holes formed in the reinforcing elements, to fix the mounting brackets to the reinforcing elements by screwing the mounting bolts.
In this prior art, a lower rigidity portion (thin-walled portion) is formed in the mounting bracket adjacent to the mounting holes, so that the pair of the second wall portions are easily bent inwardly toward the reinforcing elements without a large screwing force. As a result, the second wall portions become in contact with the reinforcing elements and the mounting brackets are firmly fixed to the reinforcing elements.
When a vibration in the vertical direction is applied to the heat exchanger from the vehicle, the reinforcing elements as well as tubes and fins (which are horizontally extending) of the prior art are likely to be bent in the vertical direction. And stress generating at the reinforcing elements, at which the mounting brackets are fixed, becomes larger. As a result, it is necessary in the prior art, to form the reinforcing elements having a higher rigidity.